Process of treating spent alkaline pulping liquors.



covered.

UNITED STATES PATENT OFFICE.

WILLIAM J. HOUGH, 0F TOLEDO, OHIO.

PROCESS OF TREATING SPENT ALKALINE PULPING LIQUORS.

No Drawing.

citizen of the United States, residing at Toledo in the count of Lucas and .State of .Ohio, have invente certain new and use-v ful Improvements in Processes of Treating Spent AlkalinePulping Liquors, of which the following is a specification.

This invention relates to a method of treating the spent liquors resulting from the manufacture of wood pulp by thesoda and sulfate processes, whereby the organic matter contained in such liquors is re- I Wood may be said to consist substantially of water, cellulose, resin and li in. The two latter substances, together, orm about the same portion of the wood as does the cellulose. When wood is pulped b a hot alkaline solution, the resinous and i eous matters are'so afiected by the chemica used that they are liquefied, while the cellulose remains practicall unaltered as a solid. The alkaline solution containing .the resinous and ligneous substances will hereinafter be spoken of as the spent liquors. The chemistr of resin and /li am is disputed. As state they are dissolve by the hot alkaline solution used in the pulping process.

Undoubtedly, resinate and lignate of soda are roducts of this reaction.

y invention consists in neutralizing the v spent liquors With an acid, whereupon the resin and hgnin'are precipitated. The precipitate is a "pasty mass and can be separated from the solutionby the ordinary methods offiltration. It is preferable that the solution be quite hot before filtering, as the preci itated resin and lignin become more solid. when the solution is in this condition, the filtration being thus greatly fa- Speoiflcatlon of Letters Patent. Patented Feb. 15, 1910. Application filed May 14, 1908. Serial No. 432,932.

cilitated. The resin and lignin, recovered as described are not now products of value. However, when destructively distilled, they yield a mixture of creosotin and rosin oil which is'paiticularly of va ue as a wood reservative. In the process of distillation, arge quantities of gas are given off which may be used to furnish heat for the reaction. Of course, in the process of precipitating the resin and lignin, the sodium salt of the precipitating acid is a product. This salt can be recovered by evaporating the solution. When the wood is pulped by the so called sulfate or 'sulfid rocess, the precipitating reagent is preferably sulfuric acid. When the alkaline liquors are neutralized with this acid, sodium sulfate is a product of the reaction. The sodium sul-' fate solution may be-evaporated to dryness, the salt then i ited with an organic substance, thus re ucing the sulfate to the sulfid and hgdroxid of soda. These latter salts may t en be used' on subsequent charges of wood. n

Claims.

1. The method described, which consists in treating a spent alkaline pulping solution with an acid to precipitate the resinous and ligneous matters contained in such solution.

2. The method described, which consists in treating a f spent alkaline pulping solution with sulfuric acid to precipitate the resinous .apd ligneous matters contained in such solutlon. a

In testimon whereof I aflix my signature, in presence 0 two witnesses.

' WILLIAM J. HOUGH.

Witnesses:

R. PEhLE HERRICK, FRANK J. KENT. 

